THE ROLE OF

ORGANOPHOSPHATE EXPOSURE

IN THE AETIOLOGY OF

DEPRESSION & SUICIDALITY

AMONGST FARM WORKERS ON

GRAPE FARMS IN THE WESTERN

CAPE PROVINCE, SOUTH AFRICA

1Mrs. Vicky Major, 2Professor Hans Kromhout, 2Dr. Tim Meijster, 3 Professor Leslie London 1 Western Cape College of Nursing / CPUT; 2Utrecht University

institute for Risk Assessment Studies, Netherlands; 3 UCT, School of Public Health and Family Medicine

To investigate whether long-term

exposure to organophosphate

pesticides (OP’s) was associated with

psychological factors or conditions

that predispose to suicide, specifically

depression, amongst farm workers on

grape farms in the Western Cape

Farm workers are often exposed to unsafe working

conditions, particularly sometimes daily exposure to OP’s

• Occupational Health and Safety Act, Act 85 of 1993

‘every employer shall provide and maintain a working

environment that is safe and without risk to the health of

its employees’

• Constitution of SA (Act 108 of 1996, ch. 2 ‘Bill of Rights’)

everyone has ‘the right to an environment that is not

harmful to their health or well-being’

• OP’s are most lethal pesticides - designed to target

nervous systems of insects, but humans equally

susceptible (neural functioning of mammals &

insects are similar)

• Globally OP’s & carbamates most commonly used

insecticide in agriculture & gardening - responsible

for 80% reported toxic exposures (Antonijevic &

Stojiljkovic 2007)

• 1999: Grape sector largest user of pesticide in South

Africa (Dalvie et al, 2009)

• Chlopyriphos, most commonly used OP in the grape

sector - associated with neurotoxic effects in humans

(Schultz et al, 2001; Dalvie et al, 2009)

• OP exposure - cause of acute and chronic poisoning

amongst farm workers and farm residents in South

Africa (Dalvie et al, 2009), Africa (Ohaya-Mitoko, 1997;

Hanshi, 2001) and globally (Stallone & Beseler, 2002)

• A relationship between OP exposure and depression

cited in global studies (Amr et al, 1997; Smits, 2000;

Jamal et al, 2002; Beseler et al, 2006 & 2008)

• Ali et al (1979) - neurotransmitters, dopamine (DA),

norepinephrine (NE) and serotonin significantly

decreased in rats 10 days after exposure to OP’s

(Depression occurs when serotonin, DA & NE are

decreased in the brain)

• Studies on humans suggest a positive association

between depression, suicide and serotonin levels in

the CNS (Oquendo & Mann 2000; Grohol 2005)

Breede Valley: Western Cape Province

Wine Grape Area : 9 / 66 farms

convenience sample

• 5 farms - Slanghoek

• 4 farms - Louwshoek

Breede Valley: Western Cape Province

Table Grape Area : 60 / 201 farms random selection

48 (80%) participated in study

• 22 farms - Hex River

• 9 farms - Orchard

• 15 farms - De Doorns

• 1 farm - Brandwacht

• 1 farm - Nuy

• Cross-sectional survey of 817 farm

workers

• Occupational & Environmental Exposure

assessed with an administered

questionnaire

• Neuropsychiatric Outcomes – current

levels of depression, impulsivity and

suicidal ideation of participants, assessed

with 7 standardised instruments

Demographic, Occupational Information (n = 817)

Gender (M:F) 486:331

Farm type workers (wine : table grape) 179:638

Age (years) 35 ±10

Cumulative Exposure

Years worked in agriculture 14 ±10

Tractor driver (222 males : 5 females ) 227 (28%)

Head (lead) sprayer (137 males : 1 female) 138 (17%)

Years worked as a tractor driver and / or

head sprayer 15 ±13

Past pesticide poisoning positively associated with

psychiatric disorders (GHQ-28; OR: 2.17) and

depression (GHQ Severe Depression Subscale;

OR: 1.62)

Positive association found between reports of

environmental exposure (smelling pesticides in the

home on spraying days) and depression (GHQ

Severe Depression Subscale) (OR: 1.66)

Female farm workers reported higher levels of

depression and suicidal ideation (p < 0.01) and

were more impulsive (p = 0.01) than male workers

– link with suicidal ideation

Female farm workers received less PPE than males

(2:3 items)

Workers who received one or no items of PPE had

increased risk of being depressed (OR: 1.90)

More females reported being treated for a

psychiatric illness (1.7:1); ‘nerves’ (7:1) and

hypertension (1.7:1)

Farm Workers not wearing appropriate

PPE while working in the vineyards

Workers on table grape farms appeared to be

more advantaged than wine grape workers

received more items of PPE (3:2, p < 0.01)

had a higher socio-economic status (4:3, p < 0.01)

Wine grape farm workers appeared to be

significantly more depressed, impulsive and had

more suicidal ideation (p< 0.01), than table grape

workers

Psychiatric illness was a significant predictor for

psychiatric disorders, (GHQ, OR: 4.83), general

distress (physical, physiological and psychological)

(BSI, OR: 3.55) and depression (OR: 2.36 – 6.02)

Low socio economic status was a significant

predictor for psychiatric disorders, (GHQ, OR: 1.62),

general distress (physical, physiological and

psychological) (BSI, OR: 1.90), depression (OR: 1.53

– 1.90) and impulsivity (BIS-II, OR: 1.48)

There was no evidence for a positive association

between cumulative pesticide exposure and any

adverse neuropsychiatric outcomes

However, a notable finding of the study was the

positive association found between reports of

environmental exposure (smelling pesticides in the

home) and depression, which could suggest that

environmental exposure may be an important cause of

depression-related symptoms in the grape farming

sector

THANK YOU

FOR

PARTICIPATING

IN THIS

SESSION